Funding agency: Austrian Science Fund (FWF) Period: Mar. 2022 - Mar. 2026 Budget: 590,725 € Function: Co-applicant / PostDoc Link:Grant no. P35401
Description
The black soldier fly (Hermetia illucens) has great biotechnological potential that is increasingly the focus of scientific attention. This insect can help to meet two challenges of our century the globally increasing amounts of organic waste that have to be managed in an economically and ecologically sustainable way, and the growing population with simultaneously rising living standards in economically poorer countries, which will make a future supply of food and feed more difficult. Larvae of the black soldier fly can utilise almost all organic waste from plant residues to slaughterhouse waste and even serve as feed for farm animals such as poultry, pigs, and fish. They have the highest levels of fat and protein known from insects and are rich in minerals. While the larvae are very robust, the flies are fragile in their adult stage. Critical, therefore, is the egg -laying phase, which is the bottleneck of the whole process. The project aims to identify chemicals produced by microorganisms that positively influence the egg- laying behaviour of the black soldier fly and to explore their applicability in breeding the fly. We combine egg-laying experiments with chemical, microbiological, genetic, and genomic analyses. Specifically, we aim to select the most attractive substrate for oviposition from promising candidates; identify the chemical substances released by this substrate that promote oviposition; and characterise the microorganisms that produce these substances; these microorganisms will then be used to produce a highly attractive substrate for oviposition. This project is the first to combine behavioural biology, ecology, chemistry, and microbiology to study the oviposition of the black soldier fly. If successful, the project will be remarkable from both an applied and a basic science point of view from an applied point of view, because the deciphering of egg-laying-regulating substances and microorganisms can lead to the development of new, also industrially relevant breeding methods, and from a basic science point of view, because we are working on a multidisciplinary case study using the latest technologies to gain insights into the chemical communication of insects and microorganisms and their behavioural consequences.
Involved students
Linda Tekaat (master thesis)
Elisa Gemassmer (master thesis)
References
2025
BugBook: Black soldier fly as a model to assess behaviour of insects mass produced as food and feed
Jeffery K. Tomberlin, Thomas Klammsteiner, Noah Lemke, Pratibha Yadav, and Christoph Sandrock
Abstract Behavioural research and its applications has a rich history in science with direct applications continuing to expand global understanding of ecosystem function, structure, and evolution. The same can be said for such research as related to the applied sciences including entomology. The purpose of this chapter is to provide context to various approaches for assessing behaviour of insects that are mass produced for food and feed. By using the black soldier fly as a model, various approaches for conducting such research are explored along with providing some perspective on the value of such data for optimising insect production. However, it should be noted that this chapter is not exhaustive with regards to variables that can be examined, or the methods employed.
@article{tomberlin_bugbook_2025,title={{BugBook}: {Black} soldier fly as a model to assess behaviour of insects mass produced as food and feed},volume={(in press)},shorttitle={{BugBook: Fly behaviour}},url={https://brill.com/view/journals/jiff/aop/article-10.1163-23524588-bja10225/article-10.1163-23524588-bja10225.xml},doi={10.1163/23524588-bja10225},language={eng},number={aop},urldate={2025-05-15},journal={Journal of Insects as Food and Feed},author={Tomberlin, Jeffery K. and Klammsteiner, Thomas and Lemke, Noah and Yadav, Pratibha and Sandrock, Christoph},month=may,year={2025},publisher={Wageningen Academic},keywords={choice test, reproduction, experimental design, Published Articles, electrophysiology, ethology},pages={1--20},dimensions=true,}
2024
Primary study on frass fertilizers from mass-reared insects: Species variation, heat treatment effects, and implications for soil application at laboratory scale
Insect farming has gained popularity as a resource-efficient and eco-friendly method for managing organic wastes by converting them into high-quality protein, fat, and frass. Insect frass is a powerful organic fertilizer that enriches the soil with essential plant nutrients and enhances plant defense mechanisms through chitin stimulation. Given the importance of frass commercialization for many insect farmers and the use of increasingly diverse organic wastes as insect feedstocks, there is a need for legal guidelines to enable clean production practices. The recent introduction of a legal definition for frass and heat treatment requirements by the EU commission marks a significant step towards standardizing its quality; however, little is known about the processes shaping its nutritional profiles and contributing to its maturation. Our study addresses key knowledge gaps in frass composition and production practices. Here, we analyzed the physicochemical, plant-nutritional, and microbiological properties of black soldier fly, yellow mealworm, and Jamaican field cricket frass from mass-rearing operations and assessed the impact of hygienizing heat treatment on fertilizer properties and frass microbiota. The results showed that frass properties varied significantly across insect species, revealing concentrations of plant-available nutrients as high as 7000 μg NH4+-N, 150 μg NO2–NO3–N, and 20 mg available P per g of total solids. Heat treatment reduced microbial activity, biomass, and viable counts of pathogenic Escherichia coli and Salmonella spp. In terms of frass microbiome composition, alpha diversity showed no significant differences between fresh and heat-treated frass samples; however, significant differences in microbial community composition were observed across the three insect species. Despite heat treatment, soil application of frass reactivated and boosted soil microbial activity, inducing up to a 25-fold increase in microbial respiration, suggesting no long-term detrimental effects on microorganisms. These findings not only enhance our understanding of insect frass as a nutrient-rich organic fertilizer but also have implications for regulatory frameworks, underscoring its promising potential for soil health and nutrient cycling. However, it is important to recognize the primary nature of this research, conducted at laboratory scale and over a short term. Future studies should aim to validate these findings in agricultural settings and explore additional factors influencing frass properties and its (long-term) interaction with soil ecosystems.
@article{praeg_frassterile_2024,title={Primary study on frass fertilizers from mass-reared insects: Species variation, heat treatment effects, and implications for soil application at laboratory scale},volume={356},copyright={All rights reserved},issn={0301-4797},url={https://www.sciencedirect.com/science/article/pii/S030147972400608X},doi={10.1016/j.jenvman.2024.120622},language={English},urldate={2024-03-21},journal={Journal of Environmental Management},author={Praeg, Nadine and Klammsteiner, Thomas},month=apr,year={2024},publisher={Elsevier},pages={120622},dimensions=true,}
2023
Microbial influences on black soldier fly reproduction: A focus on egg surface colonization
Carina Desirée Heussler*, Thomas Klammsteiner*, Katharina T. Stonig, Heribert Insam, Birgit C. Schlick-Steiner, and Florian M. Steiner
Background: The growing global population increases the demand for protein, while the management of organic waste is becoming more challenging. Alternative protein sources are needed to reduce the negative environmental impact of food production. Lately, the black soldier fly (BSF) has been proposed as an ideal animal protein substitute due to its ability to consume and reduce diverse organic waste, thus solving two problems at the same time. Mass-rearing of BSF depends on flourishing reproduction, which is influenced by environmental and physiological factors. BSF females oviposit egg clutches near decomposing organic matter and conspecific eggs, with studies highlighting the crucial role of microorganisms in oviposition. In this study, we focus on the surface microbiota of the egg and its origin. We investigated if the microbiota are inoculated before, during, or actively after oviposition. For this purpose, we analysed the microbiota in the haemolymph and gut of larvae raised on sterilized and non-sterilized feed, the pupal cell pulp, the wash of the egg-laying apparatus and the eggs directly collected after oviposition, the ovarian eggs and the empty female abdomen, the eggs with contact to adult BSF, and sterilized eggs to assess the stage in BSF development during which the microbial colonization of the egg surface occurs. Results: Our analysis revealed distinct bacterial profiles across life stages, indicating a shift from larval dominance of Enterobacteriaceae to a dominance of Burkholderiaceae on all analysed eggs. On genus level, larval stages were characterized by Morganella sp., Escherichia sp., and Proteus sp., transitioning later to less diverse communities in egg samples predominated by Burkholderia-Caballeronia-Paraburkholderia sp. While eggs from clutches and directly collected from the ovipositor generated viable offspring, surface sterilized eggs and eggs dissected from the ovary turned out to be nonviable. In microbiological cultivation trials, the established sterilization protocol was shown to be effective in removing viable microorganisms from the egg’s surface. Conclusion: Our study reveals that while a predominant microbiota persists throughout all life stages, its composition undergoes a progressive transformation during maturation, particularly before oviposition. Gaining deeper insights into egg surface microbiota and the cues guiding oviposition has the potential to boost egg production and simplify mass harvesting of BSF larvae.
@article{heussler_microbial_2023,type={preprint},title={Microbial influences on black soldier fly reproduction: A focus on egg surface colonization},copyright={All rights reserved},shorttitle={Microbial influences on black soldier fly reproduction},url={https://www.researchsquare.com/article/rs-3314156/v1},urldate={2023-09-21},publisher={Research Square},author={Heussler*, Carina Desirée and Klammsteiner*, Thomas and Stonig, Katharina T. and Insam, Heribert and Schlick-Steiner, Birgit C. and Steiner, Florian M.},month=sep,year={2023},doi={10.21203/rs.3.rs-3314156/v1},dimensions=true,}
Frass fertilizers from mass-reared insects: species variation, heat treatment effects, and implications for soil application
Insect farming has gained popularity as a resource-efficient and eco-friendly method of managing organic wastes by converting them into high-quality protein, fat, and frass. Insect frass is a powerful organic fertilizer, enriching the soil with essential plant nutrients and enhancing plant defense mechanisms through chitin stimulation. Given the importance of frass commercialization for many insect farmers and the use of increasingly diverse organic wastes as insect feedstock, the need for legal guidelines to enable clean production practices has emerged. The recent introduction of a legal definition for frass and heat treatment requirements by the EU commission marks a significant step towards standardizing its quality. However, frass composition is influenced by numerous factors, and little is known about the processes shaping its nutritional profiles and contributing to its maturation. Here, we analyzed the physicochemical, plant-nutritional, and microbiological properties of black soldier fly, yellow mealworm, and Jamaican field cricket frass from mass-rearing operations and assessed the impact of hygienizing heat treatment. Frass properties varied significantly across insect species, revealing concentrations of plant available nutrients reaching as high as 7000 μg NH4+, 150 μg NO2-NO3–N, and 20 mg P per g of total solids. Heat treatment affected microbial activity by reducing basal respiration and microbial biomass carbon, but also reducing viable counts of pathogenic E. coli and Salmonella sp. In terms of microbiome composition, alpha diversity showed no significant differences between fresh and heat-treated frass samples within each insect species, but significant distinctions were observed across the three insect species. The soil application of frass reactivated and boosted soil microbial activity, suggesting no long-term detrimental effects on microorganisms. These results further highlight the potential of insect frass as nutrient rich organic fertilizer, with promising benefits for soil health and nutrient cycling.
A comparative study of effects of biodegradable and non-biodegradable microplastics on the growth and development of black soldier fly larvae (Hermetia illucens)
Carina D. Heussler, Isabel L. Dittmann, Bernhard Egger, Sabine Robra, and Thomas Klammsteiner
Purpose: This study aimed to investigate the digestion process of biodegradable and non-biodegradable microplastics (MPs) within black soldier fly larvae (BSFL) and assess their impact on larval growth and development. The goal was to understand the fate of MPs within BSFL, considering their potential for waste conversion polluted with MPs. Methods: BSFL were exposed to two types of MPs, and their growth, development, potential accumulation and excretion of MPs were monitored. Results: The findings revealed that the MPs accumulated solely in the larval gut and had no adverse effects on the growth and development of BSFL. Larvae efficiently excreted MPs before reaching the pupation stage. Conclusion: This research emphasizes the potential of BSFL as a bioconversion agent for organic waste, even in the presence of MPs. The effective excretion of MPs by BSFL before pupation suggests their ability to mitigate potential harm caused by MP accumulation. The fact that BSFL may excrete MPs before pupation would contribute to their safe use as animal feedstock. A careful evaluation of the effects of using BSFL reared on contaminated substrates especially containing visually non-detectable residuals like nanoplastics, chemicals or toxic metals and further examination of the broader implications for waste management and sustainable livestock farming remains important.
@article{heussler_comparative_2023,title={A comparative study of effects of biodegradable and non-biodegradable microplastics on the growth and development of black soldier fly larvae (<i>Hermetia illucens</i>)},copyright={All rights reserved},issn={1877-2641, 1877-265X},url={https://link.springer.com/10.1007/s12649-023-02296-0},doi={10.1007/s12649-023-02296-0},language={en},urldate={2023-11-06},journal={Waste and Biomass Valorization},author={Heussler, Carina D. and Dittmann, Isabel L. and Egger, Bernhard and Robra, Sabine and Klammsteiner, Thomas},month=oct,year={2023},publisher={Springer},dimensions=true,}
2022
Decrypting the microbiota on the black soldier fly’s (Hermetia illucens L., Diptera: Stratiomyidae) egg surface and their origin during development
Carina D. Heussler*, Thomas Klammsteiner*, Katharina T. Stonig, Heribert Insam, Birgit C. Schlick-Steiner, and Florian M. Steiner
The increasing global population leads to a soaring demand for protein for food and feed, and also challenges in organic waste management are growing. All this leads to environmental stress, causing biodiversity loss and an increase in greenhouse gas emissions. Alternative and sustainable animal protein sources are needed to reduce the negative environmental impact of food production. In the last years, the black soldier fly (BSF) has been proposed to substitute animal protein, since BSF may consume and reduce a variety of waste organic matter. Successful industrial rearing of BSF depends on a flourishing reproduction of adults, which is influenced not only by environmental but also by physiological factors. The BSF female oviposits single eggs into clutches close to decomposing organic matter and conspecific eggs. Studies have shown that microbes play a significant role in the oviposition of BSF eggs. In this study, we focus on the surface microbiota of the egg and its origin. We investigated if the microbiota is inoculated before, during, or actively after oviposition. For this purpose, we analysed the microbiota in the larval haemolymph and the gut of larvae raised on sterilized and non-sterilized feed, the pupal cell pulp, the wash of the egg-laying apparatus and the eggs directly collected after oviposition, the ovarian eggs and the empty female abdomen, the eggs with contact to adult BSF, and sterilized eggs. The bacterial communities were identified through 16S rRNA gene sequencing to assess the stage in BSF development during which the microbial colonization of the egg surface occurs. We demonstrated that bacteria differ among life stages resulting in a shift during BSF development from dominance of Enterobacteriaceae during the larval stage to dominance of Burkholderiaceae spp. in all analysed eggs. A predominant microbiota is present before oviposition and persists through all life stages, however, the overall population’s structure successively shifts during development. A better understanding of egg surface microbiota and oviposition attractants could significantly increase egg production and facilitate the mass harvesting of BSF larvae.
